(Bq) Becquerel is the system international (SI) since 1985 new unit of radioactivity. 1 becquerel is equal to 1 disintegration per second.
1 Bq = 0.027 x10^-9 Ci (Curie).
In medicine and radiation protection the SI measurement units of becquerel, gray and sievert (should) have replaced the conventional units of curie, rad and rem.

To convert:


See also Gray, Sievert, Roentgen Equivalent In Man, Radiation Absorbed Dose, Count and Becquerel Antoine Henri.

Discovered the radioactivity in 1896.

(C, c, Ci) Curie is an obsolete unit of radioactivity; superseded by the SI unit becquerel.
1 curie is 3.70 x10¹⁰ disintegrations per second or 37,000 MBq. Formerly it was defined as the radiation emitted by 1 g of radium.
The curie is originated on Marie (1867-1934) and Pierre (1859-1906) Curie, (French chemists and physicists and Nobel laureates).

See Becquerel.

Activity is the rate of radioactive decay or the emission rate of a radiation from radioactive material. The cumulated activity is useful for nuclides that emit multiple radiations per disintegration.
The units for activity are the curie (Ci) and the becquerel (Bq).

Henri Becquerel demonstrated beta particles in 1900. Identical with electrons is there negative charge at -1. Their mass is 549 millionths of one AMU, 1/2000 of the mass of a proton or neutron. Beta particles consist of high energetic electrons emitted by radioactive nuclei or neutrons. By the process of beta decay, one of the neutrons in the nucleus is transformed into a proton and a new atom is formed which has one less neutron but one more proton in the core. Beta decay is accompanied by the emission of a positron (the antiparticle of the electron), a positive charged antineutrino. Beta particles have a greater range of penetration than alpha particles but less than gamma rays or x-rays. The name beta was coined by Rutherford in 1897. The traveling speed of beta particles depends on their energy. Because of their small mass and charge beta particles travel deep into tissues and cause cellular damage and possible cancer.

See also Radiation Shielding.